Cable ties are well-known for use in bundling objects such as cable bundles. Integral one-piece cable ties typically include a cable tie head with a strap insertion passageway that extends perpendicular to the strap. However, some cable tie heads have an in-line strap insertion passageway that is parallel to the strap. These in-line cable ties often have a lower head profile. Either type of one-piece cable tie typically includes either a fixed wedge locking mechanism that mates with teeth on a single side of the cable tie strap or a hinged flexible wedge locking mechanism that hingedly mates with teeth on a single side of the cable tie strap.
Fixed wedge designs can achieve high loop tensile strength compared to flexible hinge wedge designs, but at the expense of a high thread insertion force. Fixed wedge designs having a single set of teeth on one side typically have a small passline clearance through the cable tie head in order to ensure loop tensile strength by maintaining connection between the fixed wedge teeth and teeth on the strap. To work effectively, this typically involves an interference fit of the strap body and teeth with the internal passageway of the head. This results in a high insertion force problem. Because of this, many fixed wedge cable tie designs require use of a tool for cable tie installation.
Flexible hinge wedge designs can achieve a lower thread insertion force because the passline clearance can be effectively increased. The flexible hinged wedge pivots out of the way during strap insertion. However, upon an attempt to withdraw the strap, the teeth of the hinged locking wedge engage corresponding teeth in the strap and urge the hinged locking wedge mechanism downward into tighter engagement with the strap and a bottom wall of the cable tie head. Thus, upon attempted withdrawal, the effective passline clearance is reduced. However, because of the flexible hinge, this type of locking mechanism typically has lower loop tensile strength compared to a fixed locking wedge.
Currently, there are no in-line threading cable ties that achieve the required tensile strength in the electrical contractor market without an excessive thread force. Thus, it would be desirable to provide a cable tie having the strength of a fixed wedge part and the thread force of a moving wedge part.
An aspect of the invention is to provide an improved cable tie, preferably an in-line style cable tie, that can achieve a high loop tensile strength and a low thread insertion force. In particular, the invention can achieve up to about 60% higher loop tensile strength than a conventional hinged locking wedge cable tie while achieving up to about a 70-75% decrease in thread insertion force compared to a conventional fixed locking wedge cable tie.
In accordance with an aspect of the invention, a cable tie with hybrid locking mechanism includes a hinged locking wedge engaging a series of teeth on one side of the strap body and a fixed locking wedge engaging a series of teeth on an opposite side of the strap body.
In accordance with another aspect of the invention, a cable tie with hybrid locking mechanism provides fixed locking wedge teeth on a bottom side of the internal passageway of the locking head and hinged locking wedge teeth on a top side of the internal passageway of the internal passageway of the locking head.
In accordance with a further aspect of the invention, a cable tie with hybrid locking mechanism provides the hinged locking wedge laterally offset from the fixed locking wedge in the direction of strap insertion.
In accordance with yet another aspect of the invention, a cable tie with hybrid locking mechanism has an increased head length to isolate tensioning and cutoff of the strap from the locking wedges. This results in a cable tie design that is more tolerant of abusive installation practices.
In accordance with additional aspects of the invention, the cable tie has substantial flexibility due to the strap teeth being provided on both sides of the cable tie body.